European Patent 1 603 781 B1 and U.S. Pat. No. 5,479,567A discloses an anti-skid control apparatus for a braking system of a vehicle having a left and right front wheels and left and right rear wheels. There are no federally sponsored research or development involved with this invention. These braking system are considered as prior art. This disclosed braking system includes: an adjustable modulator (not shown), for increasing a hydraulic pressure to oil cylinders of the left and right, and front and rear wheels of the vehicle in a hydraulic pressure increase mode, holding as is the current value of the hydraulic brake pressure in a hydraulic pressure holding mode, and for reducing the hydraulic brake pressure to the oil cylinder of said left and right, and said front and rear wheels of said vehicle in a hydraulic pressure reduction mode; a detection means for detecting the speed of said left and right, and said front and rear wheels of said vehicle; a slip detection means for judging by evaluating signal outputs from said detection means whether or not a slip of the extent to which anti-skid control is necessary has been generated in any of the front, rear, left and right wheels of said vehicle and a controller which controls the modulator based on the judged result of said slip detection means, and which selects and sets one of said hydraulic pressure increase mode, said hydraulic pressure holding mode and said hydraulic pressure reduction mode for each wheel. The controller provides an anti-skid control setting means for setting an anti-skid control for the wheel; the slip detection means judged that the anti-skid control is necessary; a hydraulic pressure control means for setting said adjustable modulator at either the pressure maintaining mode or the pressure reduction mode with regard to the wheel for which the anti-skid control has been set by said anti-skid control setting means until the slipping which triggered the anti-skid control disappears, and, when the slipping disappears, for setting the adjustable modulator at the pressure increase mode in condition that the wheel speed of the wheel is increasing; and a pressure increase restriction means for determining whether slip is increasing at the pair of front or rear wheels to which the wheel the pressure increase mode is set does not belong, and converting the pressure increase mode to either the pressure maintaining mode or the pressure decrease mode if the slip at the pair of front or rear wheels is increasing.
An Anti-lock Brake System (ABS) is often included as standard equipment on new vehicles. However, an ABS alone has proven to be ineffective with controlling a vehicle's skidding on slippery rigid surfaces such as wet roads, ice or snow covered roads and non-ridge surfaces such as sand and loose gravel. The obvious problem is that standard rubber tires or even specialize tires with customize treads offer very little traction on the above mention road surfaces especially during heavy braking conditions which in most cases lead to an out of control skidding vehicle. This situation can only be remedied with the intervention of a device that can re-establish traction (friction) between a wheel and its supporting surface and then applying a combination of anti-lock brake with skid control and locking brake when the demand for a rapid stop on slippery road surfaces is required. Hence the invention provides a solution to the problem by providing an adjustable wheel traction system integrated with prior-art ABS technology. The new integrated braking system invention is called a universal braking system (UBS).